<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
  /* 伪类 */
  button:active {
    background-color: red;
    color: white;
  }
  p:hover {
    background-color: yellow;
  }
  ::selection {
    background-color: blue;
    color: white;
  }
  input:focus {
    border: 2px solid blue;
  }
  input:chedcked + label{
    font-weight: bold;
  }
  li:not(:last-child) {
    margin-bottom: 10px;
  }
  li:nth-child(odd){
    background-color: lightgray;
  }
  </style>
</head>
<body>
  <div class="container">
    <h1>伪类选择器示例</h1>
    <button>点击我</button>
    <p>鼠标悬浮在这里</p>
    <input type="text" placeholder="输入框" autofocus>
    <input type="checkbox" id="option1">
    <label for="option1">选项1</label>
    <input type="checkbox" id="option2" checked>
    <label for="option2">选项2</label>
    <ul>
      <li>列表项1</li>
      <li>列表项2</li>
      <li>列表项3</li>
      <li>列表项4</li>
    </ul>
  </div>
</body>
</html>